Hi - have been having an issue since 128 where I can't select items in certain menus in Firefox with the mouse. Each time I open Firefox, it works once. Subsequently, the focus in the menu is completely off from where I put my mouse, and I can't click anything. (I would upload a video, but there doesn't seem to be a way). An example of the behavior is: -hamburger menu open. Mouse is on 'Translate page', but focus is on 'save page as'. * This happens with both the trackpad and the mouse. * I don't experience this issue with other applications. * I can navigate some of the menu options with the keyboard. For example, in the Bookmark menu I can select Save, but not Remove bookmark. * I don't have any issue with the main nav bar (File, Edit, etc) This applies to for example: Save bookmarks (cmd+d), Hamburger Menu, Update reminders, and the new Translation dialog (have attached screenshots of some affected items). I can't inspect them to see if they are all the same component that is causing the issue, because they disappear if you choose Inspect. (I'm unable to see a "Disable popup autohide" setting in my meatball menu, as described [https://discourse.mozilla.org/t/how-can-i-inspect-the-popup-of-an-addon/34134/2 here]). I also tried the steps listed [[https://support.mozilla.org/en-US/questions/957538]] here. Things I have tried: * resetting PRAM/SMC just in case it's my machine * disabling hardware acceleration * starting in safe mode * refreshing Firefox * updating to the latest version (thrice) machine: MacBook Pro Retina, 13-inch, Mid 2014